21232021009 has 2 divisors, whose sum is σ = 21232021010. Its totient is φ = 21232021008.

The previous prime is 21232021007. The next prime is 21232021039. The reversal of 21232021009 is 90012023212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13030907409 + 8201113600 = 114153^2 + 90560^2 .

It is a cyclic number.

It is not a de Polignac number, because 21232021009 - 2¹ = 21232021007 is a prime.

It is a super-2 number, since 2×21232021009² (a number of 21 digits) contains 22 as substring.

Together with 21232021007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21232021001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616010504 + 10616010505.

It is an arithmetic number, because the mean of its divisors is an integer number (10616010505).

Almost surely, 2^21232021009 is an apocalyptic number.

It is an amenable number.

21232021009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21232021009 is an equidigital number, since it uses as much as digits as its factorization.

21232021009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The spelling of 21232021009 in words is "twenty-one billion, two hundred thirty-two million, twenty-one thousand, nine".